Harmonic damper

The harmonic balancer often serves as a pulley for the accessory drive belts turning the alternator, water pump and other crankshaft driven devices.

Impulses applied to the crankshaft by the connecting rods will "wind" this spring, which will respond (as a spring–mass system) by unwinding and re-winding in the opposite direction.

Each time a cylinder fires, the force of the combustion is imparted to the crankshaft rod journal.

In some engines, the torsional motion of the crankshaft at certain speeds can synchronize with the harmonic vibrations, causing a resonance.

The mass counteracts the torsional crank motions and in concert with the energy dissipating element absorbs the harmonic vibrations.

The first three use older technology; First is the liquid type damper which surrounds the mass immersed in the housing which is then bonded or welded together.

Many of the advances were led by the Japanese manufacturers as they have made quality and durability the cornerstone of their programs.

The Japanese advanced the proliferation of forged crankshafts with rotating assemblies at 0 gram balance.

Adding these additional forged components improves the engine’s rigidity and further reduces concern about crankshaft damage.

With the advent of computer aided design and finite element analysis, manufacturers can now find and re-engineer weaker areas.

Regardless of some of these improvements, certain engines, like the traditional V8, have a firing order prone to excessive harmonics by nature necessitating the use of this device.

The flat plane V8, traditionally used in more exotic engines, does not suffer from the excessive harmonics and therefore may use a solid undampened device.

OE dampers are predominantly made using rubber as the bonding agent between the inner hub and the outer mass.

Both Frederick Henry Royce and Frederick W. Lanchester have strong claims to the invention of the vibration damper, with the latest research showing Rolls-Royce using a crankshaft slipper (friction) vibration damper on their 1906 30HP models; however, Royce had not submitted it for patent.